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UNITED STATES PATENT Orrics.

THOMAS P. MILLIGAN, on SOUTH ORANGE, NEW JERSEY.

Y PROCESS OF PREPARING GLUE=STOCK.

SPECIFICATION forming part of Letters Patent NO. 379,021 dated March 6, 1888.

Serial No. 252,595. (No specimens.)

To all whom it may concern:

Be it known that I, THOMAS P. MILLIGAN, a citizen of the United States, residing at South Orange, Essex county, New Jersey, have invented certain new and useful Improvements in the Preparation of Glue-Stock, fully described in the following specification.

' My improvement consists in a novel treatment;of glue-stock for expelling the animal fluids,which are liable to cause decomposition, and also in processes for expelling the tallow contained in the pores of the stock, and for cleansing the grease from the exterior of the same.

It is a-well-known fact that gluestock has been heretofore commonly treated to a digest in the milk of lime for several weeks, then washed and dried. Unless dried it was found that the injurious-fluids still present in the stock would come out in the boiling and operate to the partial destruction of the gelatine forming and deprive it of the setting quality. If this process has been properly conducted, the stock,when dried,may be converted into gelatine, glue, or sizing by soaking in coldwater and boiling. The resulting solution can then be chilled, cut into sheets, and dried on nets.

My process differs from the above and all other processes in almost every essential particular, as will be seen in the following description,"and that each step may be clearly understood I Will take for illustration the treatment of fresh pieces and fleshings from the tanners beam. This stock is as difficult to prepare as any, and to succeed in producing good results from it will enable any one skilled in the art to apply my process successfully to any other kind of glue-stock. If we now examine this stock we shall find that it contains about three times its dry weight of water, a large portion of which it has absorbed in the sweating and lime bath to which it has been treated by the tanner while still part of the hide. There is also in this stock (What is found in all green hides) the water of composition, which from its acidity and acrid nature is very injurious to gelatine, a large percentage of acid, grease, and tallow. These, with a strong trace of lime, must be removed before the stock will be in proper condition for boiling.

As a preparatory step I first wash the stock clean in cold water. This may be done in a tank or washer made for the purpose, and there being nothing novel in washing stock in cold water I do not embrace this preliminary step in my process, which may be considered as commencing with a shrinking of the stock effected by the action of very hot water or by steam. In using hot water-I place the wet stock in a basket or other vessel made in convenient form of wire, rattan, or other suitable material, with interstices small enough to prevent the escape of the stock, while sufficiently large to freely admit the passage of water.

The receiver containing the stock is now conveyed to a tank of water about boiling-point and plunged in. The stock almost instantly contracts and hardens, losing about forty per cent. of watery fluids. Less than one minute is ordinarily required for this operation, when the receiver may be drawn up and the stock placed on a drainer ready to be conveyed to the dry-loft. In using steam for the shrinking process'I find that a jet from a pipe or steam hose directed upon a thin layer of stock placed on a slanting floor is as easy and effective away as any. The stock under this treatment acts the same as in the hot-water bath, and the effect produced is precisely the same. This step of the process may be practiced at the tanneries, Where the stock is collected by the glue-maker, and results in a considerable saving in the transportation of the stock to the glue-factory, asit greatly improves the condition of the stock for handling by hardening the tissues and diminishes the bulk and Weight of the stock over forty per cent. I now convey the stock to a loft heated by steam and properly ventilated, the stock being exposed to heated air on frames similar to those used for drying glue, the temperature of the loft to range from 125 to about 170 Fahrenheit, for this is hot enough to melt the tallow and extract it from the body of the stock. The high temperature also changes its nature, so that it may be easily removed by the alkali bath. Good results, however, can be obtained by drying in the open air and under a summer sun. The stock being now bone dry, I subject it to the action of an alkali bath at about boiling-point, and for this purpose I prefer to use Sal-soda, and if the water is natnrally soft twelve pounds to one hundred gallons of water will be found suffieient. If hard, use a little more.

The stock is placed in a receiver (similar to the one described for use in hot-water bath) and lowered into the boiling alkali, where it is left for about ten minutes, or, if the stock is very greasy, a little longer, the object being to remove grease and cleanse the stock from all deleterious matters without injury to the glueyielding tissues. The dry condition of the stock permits this to be accomplished thus quickly and effectually. I now plunge the stock, which is still in the receiver, into a bath of hot water to rinse off the alkali and any adhering grease, taking it out almost immediately. I rinse off in cold water, and then the stock is ready for a final bath in alum-water. This alunrwater I prepare by dissolving ten pounds of alum for every one hundred gallons of water contained in the tank. The stock is allowed to remain in this bath until hard. This will usually be in about twenty minutes, after which I return the stock to the dry-loft, if it is to be kept for future use or sale, and dry it. It will then keep for years and be ready for conversion into gelatine, glue, or size at any time. If, however, the stock is to be made into gelatine, glue, or size immediately, the second drying is not necessary. In such case the stock can be taken from the alum bath and boiled and a beautiful clear solution will be obtained, which will set hard when cold, and may be cut and dried on nets.

It will be seen in following out my improvement that I first drive out of the stock all injurious fluids, and then byimmersing the dry stock in a boiling alkali bath the interior of the stock is reached and acted upon to neutralize any acid substances remaining therein, while the grease adhering to the exterior of the stock is floated off and removed.

I am aware thatitis not new to treat grease with alkali in the art ot'soap-making to cause the union of the fat and alkali to produce a useful product; and I am also aware that a bath of alkali has been used, as in Patent No. 246,182, dated August 22, 1881, to neutralize the earot or nitrate of mercury in fur pelts, and I therefore disclaim such uses of the alkali. In'my invention the gluestock is treated in a dry state, to prevent the penetration of the alkali into its substance, and the grease found upon my glue-stock, and which is removed by the alkali, is a noxious and superfluous ingredient, and is not utilized, as in soap-making.

Having thus set forth my invention, what I claim herein is-- 1. The treatment of glue-stock to expel the contained fluids, consisting in the application to the stock of hot water or steam at a temperature to produce a sudden contraction of the tissues, substantially as herein set forth.

2. The treatment of glue-stoek to remove the fatty ingredients, which consists in drying the stock at a temperature suffieientl y high to melt the tallow contained therein, and to thus separate the same from the stock, substantially as herein set forth.

3. The method herein shown and described for removing the grease from glue-stoelgwhich consists, first, in drying the stock at a temperature sufficiently high to melt the tallow contained therein, to separate the same from the stock, and, secondly, in immersing the stock in a dry state in a bath of hot alkali to melt and disengage the grease adhering thereto, substantially as herein set forth.

at. The treatment of glue stock to expel the contained fluids and separate the body of the tallow therefrom, consisting, first, in the application to the stock of hot water or steam at a temperature to produce a sudden contraction of the tissues, and, secondly, in drying the same stock at a heat suffieiently high to melt the tallow contained therein, as and for the purpose set forth.

5. The treatment of glue-stock to fit it for boiling, which consists, first, in the application to the stock of hot water or steam at a temperature to produce a sudden contraction of the tissues; secondly, in drying the same stock at a heat suffieiently high to melt the tallow contained therein, and, thirdly, in immersing such dry stock in a bath of hot alkali to separate the grease therefrom, as and for the purpose set forth.

6. The treatment of glue-stock to fit it for boiling, which consists, first, in the application to the stock of hot water or steam at a temperature to produce a sudden contraction of the tissues; secondly, in drying the same stock at a heat sufficiently high to melt the tallow contained therein; thirdly, in immersing such dry stock in a bath of hot alkali to separate the grease therefrom, and, fourthly, the treatment of said stock to a bath of alum-water to neutralize the alkali and harden the stock, substantially as herein set forth.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

THOMAS P. MILLIG AN.

\Vitnesses:

L. LEE, HENRY J. MILLER. 

